Owners of small pets, such as cats and dogs, must provide a sanitary facility for use by the animal, if that animal spends any substantial amount of time indoor. These sanitary facilities are commonly known as litter boxes, and usually comprise an open-topped box for holding a quantity of disposable litter for use by the animal. This litter, as it is commonly known, may be one of the commercially-available processed granular mineral materials of the kind well known to cat owners in particular, or may comprise a naturally-occurring material such as sand or the like. The commercially-available processed animal litters usually are preferred by pet owners, because those litter materials are absorbent and are intended to clot with the absorbed urine so that the clots form solid clumps of waste products that are readily removable from the litter box. Commercial litter materials also frequently include a deodorizer for neutralizing offensive odors frown the litter box, thereby reducing the need for frequent cleaning of that box.
Cleaning an animal litter box, especially one used by cats, requires digging through the litter with a scoop or sifter to locate and remove solid waste products from the litter. Those waste products, including feces as well as clotted litter and urine, then are placed in a suitable bag or other waste container for disposal. This task is unpleasant and time-consuming, and requires some care to avoid spilling the granular material or the removed waste products onto the floor surrounding the litter box. Furthermore, the scoops or other implements used to extract the waste products from the litter need to be stored in some sanitary manner after each such use.
The prior art has recognized the problems associated with litter boxes. For example, U.S. Pat. No. 4,817,560 to Prince et al. discloses a litter box sifter in the form of a basket with a gridlike bottom and sides. This sifter basket is square or rectangular in shape, and fits within a litter box wherein the sifter basket conforms generally to the internal dimensions of the litter box. The sifter basket is lifted from the litter box to remove solid waste products from the litter box. According to that patent, the sifter basket is returned to the litter box by pressing the basket down into the box through the litter already in place within the box. However, it can be difficult to force the basket downwardly to the bottom of a closely-conforming box filled with litter, even when exerting substantial downward force on the basket.
Accordingly, it is an object of the present invention to provide an improved litter box.
It is another object of the present invention to provide an improved removable screen for use with a litter box.
It is a further object of the present invention to provide a litter box with a removable screen that fits within the litter box during normal use of the box and is relatively easily replaced in the litter box after withdrawing the screen to remove solid waste products.
It is a further object of the present invention to provide an animal litter box with a removable screen and a shield to cover portions of the litter box not containing the screen, so as to prevent unwanted ejection of litter material.
The foregoing and other objects of the present invention will become more readily apparent from the following discussion.
Stated in general terms, the present invention comprises a litter screen having a body of circular shape, such as a right circular cylinder or frustocone. This litter screen fits within a litter box that may be conventional in shape, and the litter screen has a perforated lower end placed adjacent the bottom of the litter box. The upper end of the litter screen body is open to allow an animal to enter and use the litter box. To clean the litter box, the litter screen is lifted upwardly from the litter box so that solid waste products are withdrawn from the litter box and remain within the litter screen on the perforated lower end while the granular litter material sifts through the perforated end to remain in the litter box. After disposing of the solid waste products thus removed from the litter box, the litter screen is returned to the litter box by placing the lower end of the screen on the litter in the box, and then thrusting downwardly the litter screen while oscillating the litter screen back and forth around its longitudinal axis. This oscillating movement significantly facilitates returning the litter screen to the bottom of the litter box, and the circular cross-section shape of the litter screen makes possible that movement within a litter box of conventional rectangular or square configuration.
Stated in somewhat more specific terms, the present litter screen has an imperforate body of generally circular cross-section and open at an upper end. The lower end of the litter screen body is covered by a screen member defining perforations sized to prevent passage of substantially all solid waste products anticipated within an animal litter box, but large enough to permit easy passage of the granular litter material commonly used in litter boxes. The structure defining that screen preferably is arcuate or curvilinear in configuration, so that the structure does not unnecessarily impede the oscillating movement while thrusting the litter screen into the litter material remaining in the litter box.
In a preferred embodiment of the present invention, the screen structure comprises a plane spiral member extending inwardly from the body to a point adjacent the center of the screen. Each adjacent flight of the spiral, as seen on a radial line extending from the center to the body, is spaced apart from adjacent flights a distance appropriate for the desired sifting action and retention of solid waste products.